Current integrated circuit (IC) designs may have circuitry with different components that may operate in different voltage domains. In order for components that operate in one voltage domain of the IC to interact with components that operate in a second voltage domain of the IC, signal conversion may be required. Signal conversion may utilize a “level shifter” in order to take an input signal in one voltage domain and generate a corresponding output signal in the second voltage domain. The signal conversion may have an associated voltage range of conversion. For example, a 1.8V input signal (e.g., logical high) in one voltage domain may be converted to a corresponding 3V output signal (e.g., logical high) in the second voltage domain. In this case, a level shifter may have a range of 1.8V to 3V. Conversion (i.e., level shifting) of further lower voltages of one voltage domain to further higher voltages of another voltage domain (or vice versa), increases the voltage range of a level shifter. Current IC designs have a need for high range signal conversion and corresponding conversion circuitry to accommodate the high range signal conversion.
A difficulty encountered by conversion circuitry that tries to convert a very low voltage signal to a very high voltage signal (e.g., high range conversion) is an issue of state instability. For example, during operation, components of the conversion circuitry may not always achieve a stable state but rather may encounter meta-stability where a state is achieved irrespective of the input. Such state instability (e.g., meta-stability) of components results in a corresponding instability of data states which cannot be relied upon. Another consideration is that circuitry for the conversion of a low voltage signal to a high voltage signal (e.g., up-shifting) is designed separately from the circuitry for the conversion of a high voltage signal to a low voltage signal (e.g., down-shifting). The use of different conversion circuitry for the up-shifting and down-shifting signal conversions (e.g., high range signals) may result in a more complex and less efficient design process and/or design flow for IC's utilizing signal conversion circuitry.
Consequently, there is the need for a conversion circuitry that can accommodate different voltage domains and different shifting operations that are performed as part of a high range signal conversion. Furthermore, there is a need that such conversion circuitry may provide reliable stability of data states as part of the high range signal conversion.